Sterilization - PowerPoint Presentation

Slide1

Sterilization

Norazli

Ghadin

Slide2

Objectives

Understand and utilize correct sterilization and disinfection techniques

Distinguish between sterilization and disinfection

List the characteristics of an ideal antiseptic

Describe sterilizing agents and rank their effectiveness

Discuss the time/temperature relationship in destroying microorganismsSlide3

Disinfection

Disinfection

is the elimination of pathogens, except spores, from

inanimate

objects

Disinfectants are chemical solutions used to clean inanimate objects (physical processes, e.g., UV radiation, may also be employed to effect disinfection)Germicides are chemicals that can be applied to both animate (living) and inanimate objects for the purpose of eliminating pathogensAntiseptics are formulated for application to living tissue

Destruction/Removal of

Harmful MicroorganismsSlide4

The Ideal Disinfectant

Resistant to inactviation

Broadly active (killing pathogens)

Not poisonous (or otherwise harmful)

Penetrating (to pathogens)

Not damaging to non-living materialsStableEasy to work withOtherwise not unpleasantSlide5

Disinfectant Performance…

Is dependent on Disinfectant concentrations

Is dependent on length (time) of administration

Is dependent on temperature during administration

(usual chemical reaction 2x increase in rate with each 10

°C increase in temperature)Microbe type (e.g., mycobacteria, spores, and certain viruses can be very resistant to disinfection—in general vegetative cells in log phase are easiest to kill)Substrate effects (e.g., high organic content interferes with disinfection—stainless steel bench easier to disinfect than turd)It is easier (and faster) to kill fewer microbes than many microbesSlide6

Other Terms

Sanitization:

Lowering of microbial counts to prevent transmission in public setting (e.g., restaurants & public rest rooms)

Degerming:

Mechanical removal of microbes, e.g., from hands with washing

Sepsis: Bacterial contaminationAntisepsis: Reduction of or Inhibition of microbes found on living tissue

Germincides

,

Fungicides

,

Virucides

Physical

versus

Chemical

disinfectants

Static

(stasis) versus

Cidal

(e.g., bacteriostatic versus bacteriocidal)Slide7

Resistance to Killing

Gram-negative bacteria (with their outer membrane) are generally more resistant than gram-positive bacteria to disinfectants and antiseptics

Stationary-phase (I.e., non-growing) bacteria generally are more resistant than log-phase (I.e., growing) bacteria

Mycobacteria, endospores, and protozoan cysts and oocysts are very resistant to disinfectants and antiseptics

Nonenveloped viruses are generally more resistant than enveloped viruses to disinfectants and antiseptics

Organic matter (such as vomit and feces) frequently affects the actions of chemical control agent

Disinfectant activity is inhibited by cold temperatures

Longer application times are preferable to shorter

Higher concentrations, though, are not always preferable to lower concentration (e.g., alcohols)Slide8

Chemical Antimicrobi

als

Agent

Mechanisms of Action

Comments

Surfactants

Membrane Disruption; increased penetration

Soaps; detergents

Quats

(cationic detergent)

Denature proteins; Disrupts lipids

Antiseptic -

benzalconium

chloride,

Cepacol

;

Disinfectant

Organic acids and bases

High/low pH

Mold and Fungi inhibitors; e.g., benzoate of soda

Heavy Metals

Denature protein

Antiseptic & Disinfectant; Silver Nitrate

Halogens

Oxidizing agent

Disrupts cell membrane

Antiseptic - Iodine (

Betadine

)

Disinfectant - Chlorine (

Chlorox

)

Alcohol

s

Denatures proteins

;

Disrupts lipids

Antiseptic & Disinfectant

Ethanol and isopropyl

Phenolics

Disrupts cell membrane

Disinfectant

Irritating odor

Aldehydes

Denature proteins

Gluteraldehyde

- disinfectant (

Cidex

)

;

Formaldehyde - disinfectant

Ethylene Oxide

Denaturing proteins

Used in a closed chamber to sterilize

Oxidizing agents

Denature proteins

Hydrogen peroxide

–

antiseptic

;

Hydrogen peroxide

–

disinfectan

;

Benzoyl

peroxide

–

antisepticSlide9

Physical Antimicrobials

Agent

Mechanisms of Action

Comments

Moist Heat, boiling

Denatures proteins

Kills vegetative bacterial cells and viruses

Endospores survive

Moist Heat, Autoclaving

Denatures proteins

121°C at 15

p.s.i

. for 30 min

k

ills everything

Moist Heat, Pasteurization

Denatures proteins

Kills pathogens in food products

Dry Heat, Flaming

Incineration of contaminants

Used for inoculating loop

Dry Heat, Hot air oven

Oxidation

&

Denatures proteins

170°C for 2 hours

;

Used for glassware & instrument sterilization

Filtration

Separation of bacteria from liquid (HEPA: from air)

Used for heat sensitive liquids

Cold,

Lyophilization

(also desiccation)

Desiccation and low temperature

Used for food & drug preservation; Does not necessarily kill so used for Long-term storage of bacterial cultures

Cold, Refrigeration

Decreased chemical reaction rate

Bacteriostatic

Osmotic Pressure, Addition of salt or sugar

Plasmolysis of contaminants

Used in food preservation (less effective against fungi)

Radiation, UV

DNA damage (thymine dimers)

Limited penetration

Radiation, X-rays

DNA damage

Used for sterilizing medical supplies

Strong vis. Light

Line-drying laundrySlide10

Moist Heat

Moist heat

kills microbes by denaturing enzymes (coagulation of proteins)

Boiling

(at 100°C, I.e., at sea level) kills many vegetative cells and viruses within 10 minutes

Autoclaving: steam applied under pressure (121°C for 15 min) is the most effective method of moist heat sterilization—the steam must directly contact the material to be sterilized

Pasteurization:

destroys pathogens

(

Mycobacterium tuberculosis

,

Salmonella

typhi

, etc.)

without altering the flavor of the food—does not sterilize (63°C for 30 seconds

)Slide11

Sterilization Times

121

o

C, 15 minutes, moist heat (but don’t start the clock until entire item is up to temp—e.g., large volumes fluid)Slide12

Filtration: Air & FluidsSlide13

Filtration

Membrane filters

These are porous membrane about 0.1mm thick, made of cellulose acetate, cellulose nitrate, polycarbonate, and

polyvinylidene

fluoride, or some other synthetic material.

The membranes are supported on a frame and held in special holders. Fluids are made to transverse membranes by positive or negative pressure or by centrifugation.Slide14
Slide15

USES

Remove toxin from bacterial cells

Sterilize drugs (antibiotic)

sterilize protein, glucose or other sugars

Sterilize media with

serum/heat sensitive substance Study virus size  separate virus from cellsSlide16

RADIATION

Energy

transmision

through a space

ruangan

Basicly all radiation can cause a death/mutation on microorganismeSlide17

EFFECT OF RADIATION

Changes

Cells membrane

inhibit DNA replication Slide18

Types of Radition

Ultraviolet (UV)

Ionizing radiationSlide19

UV

Naturally from the sun.

MoA

;

Induction of

dimer thymine on DNA chain (mutation):  inhibit DNA replication cell death.not all organisme can be kill. Wavelength used (260 nm)Slide20

UV: MERCURY LAMP

240 – 280 nm

To decrease bacterial volume in atmosphere, operation theatre, nursery, restaurant & food factory.

weakness

: Low penetration power.Stop by glass, paper, dust or stainCan only penetrate a few milimeter of solution.Slide21

UV

Adjacent bases

bond with

each other, instead of across the “ladder.” makes a bulge, and the distorted DNA molecule.Cant replicateMEDA 1012:MEDICAL MIKROBIOLOGISlide22

IONIZING RADIATION

X-RAY and gamma radiation (



).

More effective than UV.

MoA: destroying by mutation or oxidation Slide23

Cont…

Efective

against SPORA.

Source : isotope Cobalt

60

. Dos 2.5 mrad.sterilizing disposable: ·  Syringe and needles ·  Chateter ·  heat sensitive itemsEXPENSIVE